Process for reducing ores.



F. E. AGNEW.

PROCESS FOR REDUCING ORES.

APPLICATION FILED JUNE II, 1915.

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UNITED STATES PATENT OFFICE. 1

FRANCIS E. AGNEW, OF LOS ANGELES, CALIFORNIA.

PROCESS FOR REDUCING ORES.

Application filed June 11, 1915.

.Reducing Ores, of which the following "is :1.

- specification.

My invention relates to a process for re-. ducing ores and in particular to a process by means of which the ore is subjected to a con tinuous reducing operation.

It is well known in the art to calcine metal ores until they are converted into the oxid state and after such conversion to reduce the same by means of asuitable reducing agent such as coke, water gas, crude oil, or hydrocarbon gas. This last step is carried on in a closed drum wherein the metal oxid is heated toa temperature suitable for the reducing reaction in contact with the reducing agents. The objection to this process 1s that the same is intermittent and that in discharging the reduced ore from the drum care must. be taken to exclude the atmosphere for otherwise reoxidation will occur.

The principal object of my invention is to devise a process for continuously reducing metal ores in which the ore'is first preheated or calcined in a furnace open to the atmosphere and thereby reduced to the oxid state. The ore containing the metal oxid is then conveyed under the exclusion of the atmosphere through a vertical shaft which is surrounded by heat insulating material so as to retain the heat of the ore as it comes from the calcining zone. at a temperature which must be sufiiciently high to effect the reducing reaction. A reducing agent is introduced and intimately mixed with the heated ore; the oxygen thereof will combine with the reducing agent, forming carbon monoxid or steam. The reduced ore is conveyed from the bottom of the vertical shaft by any suitable means to a cooler where it is cooled either in a non-oxidizing gas or under the exclusion of the atmosphere. It is essential that the atmosphere be excluded from the time that the calcined ore leaves the calcining apparatus until the reduced ore leaves the cooler. It should be noted that the volumes of vapor and gas introduced or generated in the vertical shaft will positively exclude the atmosphere since the vertical shaft is open at the top only and here Specification of Letters latent.

Patented Mar. 7,1916. Serial No. 33,501.

the ascending volume of gas will prevent any access of the air'from the top.

In the accompanying drawings which form a part of this specification I have illustrated a convenient and practical apparatus for carrying out the process.

Figure 1 shows a vertical section of the apparatus. Fig. 2 is a detail view of the twyer supplying the reducing agent to the vertical shaft. Fig. 3yis a horizontal section of the shaft taken on line 33 of Fig. 1.

The metalliferous ore is fed through a chute 10 into a rotating cylinder 11 slightly inclined and lined with refractory material such as fire brick. At the lower end conduits 12 and 14 provided with nozzles supply fuel and air, respectively. The ore is thoroughly calcined and in the case of carbonates, sulfates, and sulfids, reduced to the oxid state. The lower end of the calciner is surrounded by a stationary hood 15 open at the lower end and communicating with the top of a vertical shaft 16 of successively in creasing cross sectional area toward the bottom, the bottom itself being in the shape of a hopper. This vertical shaft or furnace consists of a metal shell 17 lined with refractory material such as fire brick 18 and is surrounded by another metal shell 19 suitably spacedtherefrom. The space between said two shells is filled with-mineral wool, ashes, or similar. heat insulating material. A suitable closed conveyer such as a scroll conveyer 21 arranged at the bottom of shaft 16 discharges the reduced ore to a cooler 22 which I have shown as constructed in the shape of the rotating cylinder slightly inclined. Suitable cooling means may be provided Within said cylinder or any other suitable cooler may be substituted therefor. At the lower end of the cooler a discharging mechanism 23 is provided discharging the cooled reduced ore without allowing the atmosphere access to the interior of the cooler. On the lower part of shaft 16 a series of horizontal roof shaped baflie plates 24 are arranged in staggered relation. Twyers 25 connected to any suitable source of oil or hydrocarbon gas project through the double Walls of said shaft and underneath the baffle plates.

Operation: The ore to be treated is crushed to suitable size and is fed through chute 10 to the preheater or calciner and heated in the presence of air to the temperaheated and brought in contact bonaceous reducing substance. Among such ores may be mentioned lead, iron and anti- ,mony.

j A continuous process of reducing metalture of the reduction of the metal which, of course, varies, depending upon the nature of the ore. For copper ores, the temperature will range from 1500 to 1600 F. From the calciner the ore falls into the reducing shaft 16 where it comes into intimate contact with the reducing agent, the hydrocarbon vaporsor water gas, that is supplied throu h the twyers 25. By reason of the fact t at the twyers are located beneath the roof shaped baffle plates 2-1 the gases and vapors will come in intimate contact with every particle of the ore, the baflle plates serving to distribute and mix the ore as it passes downwardly to conveyer 21. The hydrocarbon vapors will reduce the oxid to the metallic state. The reduced ore is cooled in cooler 22 and after cooling discharged. The hydrocarbon vapors and gases mixed with steam and carbon monoxid pass upwardly through the narrow opening at the top of shaft 16 and effectively prevent atmospheric air from having access thereto. The cooler 22 is either closed to the atmosphere or is filled with a non-oxidizing gas, thus preventing a reoxidation of the ore after the reducing action. The hydrocarbon gas and vapor mixed with carbon monoxid is burned in the ca-lciner 11, and, in conjunction with the fuel introduced through nozzles 12, serves to preheat or calcine the ore in the calciner. 1

It is thus seen that I have provided an eflicient and simple process and apparatus for carrying out the reduction of metal ores in a continuous manner. This process is applicable to the treatment of all ores which will not tend to form carbids when highly with the carliferous ores comprising heating the crushed ore to the temperature of reduction of the metal contained therein,

ore under exclusion o assing the heated the atmosphere through a reaction zone in intimate contact .with a reducing agent introduced at ordinary t peratures, whereby the oxid 'of the metalis reduced to its etallic state, and

passing the reduced ore under the exclusion liferous ores comprising heating the crushed ore in the resence of airto the temperaofair through a cooling zone.

A continuous process of reducing metalture of re notion of the metal contained therein,'passing the heated ore under the exclusion of the atmosphere through a reaction zone in intimate contact with gaseous hydrocarbon introduced at ordinary temperatures, whereby the, oxid of the metal is reduced to its metallic state, and passing the reduced ore under the exclusion of air through a cooling zone.

3. A process of reducing metalliferous ores comprising heating the crushed ore in the presence of air to the temperature of reduction of the metal contained therein, passing the heated ore under exclusion of the atmosphere through a reaction zone in intimate contact with a gaseous hydrocarbon introduced at ordinary temperatures, whereby the oxid of the metal is reduced to its metallic state, and passing the reduced ore through a cooling zone in the presence of a nonoxidizing gas.

4. A process of reducing metalliferous ores comprising heating the crushed ore in a preheating furnace in the presence of air to the temperature of reduction of the metal con-' tained in said ore, passing said ore, while agitating the same, through a reduction furnace under the exclusion of air, surrounding said reduction furnace with heat insulating means, introducing a reducing agent at ordinary temperatures to said reduction furnace, and passing the reduced ore through a cooling zone in the presence of a non-oxidizing gas.

5. A process of reducing metalliferous ores comprising heating the crushed ore in a preheating furnace in the presence of air to the temperature of reduction of the metal contained in said ore, passing said ore, while agitating the same, through the reduction furnace under the exclusion of air, introducing a reducing agent at ordinary temperatures to said reduction furnace, and passing the reduced ore through a cooling zone in the presence of a non-oxidizing gas.

6. A process of reducing metalliferous ores comprising heating the crushed ore in a preheating furnace in the presence of air to the temperature of reduction of the metal contained in said ore, passing said ore, while agitating the same, through a reduction-furnace under the exclusion of air, surrounding said reduction furnace with heat insulating means, introducing a reducing agent to said reduction furnace, and passing the reduced ore through a cooling zone in the presence of a non-oxidizing gas.

In testimony whereof I have signed my name to this specification. 

